Improvement in steam-boilers



T. w; PRATT.

Steam-Boilers.

N0. 142,273. Patented August26,l873'.

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AM. PHUTDLIT/IOERAFl/IC .00. M Y. (osaanmz's Pkacsss) vertical flues.

UNITED STATES PATENT @FFIGE.

THOMAS W. PRATT, OF BOSTON, MASSACHUSETTS.

- IMPROVEMENT IN STEAM-BOILERS.

Specification forming part of Letters Patent No. 142,273, dated August26, 1873; application filed July 11, 1873.

To all whom it may concern:

Be it known that I, T. WILLIS PRATT, of Boston, in the county of Suffolkand State of Massachusetts, have invented certain Improvements inSteam-Boilers of which the following is a full, clear, and exactdescription, reference beinghad to the accompanying drawin gs makingpart of this specification, in which--- Figure 1 is a side elevation ofa steam-boiler made in accordance with my invention. Fig. 2 is a frontelevation of the same. Fig. 3 is a vertical section on the line as m ofFig. 2.

The most common forms of steam boilers now in use are, thelocomotive-boiler, with horizontal flues, and the cylindrical boiler,with Many marine boilers are made like the locomotive-boiler, and manywith both horizontal fire flues, combined with vertical water-tubes; butit is believed that all have some horizontal surfaces, where sedimentwill lodge, or narrow vertical water-legs, which easily become clogged,or angular, flat, or level spaces in the fire-tubes, where ashes willcollect.

The chief requisites of a perfect steam-generator may be enumerated asfollows: First, it should be simple and easy of construction,

\ so as to afford the greatest facility for repairs. Second, the furnaceshould be inclosed within the shell of the boiler, to economize heat.Third, the arrangement of the flues should be such as to induce the mostrapid circulation, and, at the same time, assist the draft. Fourth,ample space should be afforded for water and steam, and a large watersurface, from which the steamcan rise. Fifth,

the interior spaces should be so arranged as to allow all foreign matterheavier than water to settle freely to the lowestpoint, from whence theblow-oft cock can easily discharge them. Sixth, that the steam should besuperheated. Seventh, that the flues should, without difficulty, be keptfree from ashes or other deposits. My invention has for its object toembrace all of the requisites above mentioned; and consists in acylindrical boiler placed in an inclined position, at an angle of fromabout thirty-five (35) degrees to about fifty-five (55) degrees with thehorizon, and provided with a furnace-space at its lower end, situatedunder the upper portion of the water-leg, whereby all sediment in thewater will be caused to slip or slide downthe surface of the lowertubesheet into the water-leg, from the lower angle of which it may bedrawn out through ablowoff cock, instead of being deposited thereon, andpreventing the direct contact of the water with the tube or crown sheet,which would soon be destroyed by the action of the fire; While the ashesand cinders will readily slide down the tubes, which are thus preventedfrom being obstructed, as is the case in horizontal boilers.

To enable others skilled in the art to understand and use my invention,I will proceed to describe the manner in which I have carried it out.

In the said drawings, A is a boiler of cylindrical form, placed at aninclination of about fifty degrees with the horizon, and provided with aseries of tubes or flues, a, extending between the upper and lowertube-sheets b c, and inclined at the same angle as the sides of theboiler, these tubes being arranged in rows, one directly over another,so as to allow of the direct ascent of the heated water, while amplespace is left between the tubes and the shell of the boiler for thecooler water to descend. The lower end of the boiler terminates in acircular waterleg, d, at the lowest point of which -is placed a blow-offcock, 0, through which all sediment deposited is drawn off.

To the front of the water-leg is fitted a firefront, h, forming thefront of the furnace B. This fire-front is lined with fire brick, and isprovided with an opening, 1', at its center for i the admission of fuel,said opening to be closed by a door, (not shown,) by which constructionthe necessity of cutting a door Way through the water-leg is avoided,the inclination of the boiler being sufficient to afford room for a doorunderneath the upper portion of the water-leg.

The shell or outer casing of the boiler should be made large enough toafford all the steam and water space commensurate with the amount ofgrate and fire surface without employing a dome or steam-chimney.

As the upper portion of the tubes pass through the steam-space is,situated above the water-line w w, the requisite amount of supervheating can be obtained.

From the foregoingit will be seen that, when my inclined cylin .lricalboiler is used, any sediment in the water will come in contact with theinclined surfaces of the tubes at, that of the bottom yy of the insideof the boiler, and that of the lower tube-sheet c,- and, instead ofremaining or permanently lodging thereon, it will slide or slipdownthese surfaces to the lowest point of the water-leg d, from which it isdrawn 0% by the cock e, thereby preventing the crown or tube sheet beingburned,incident to the employment of a vertical'cylindrical boiler. Theashes and cinders, also, are prevented from accumulating in the flues ofmy inclined boiler, as they slide back down into the fire, or arecarried away through the smokepipe; consequently the flue-passages arenot contracted, as in the case of the horizontal cylindrical boiler.

THOMAS WILLIS PRATT. In presence of- N. W. STEARNS. W. J. CAMBRIDGE.

